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Muscovite Pseudomorphs After Staurolite As A Record Of Fluid Infiltration During Prograde Metamorphism, Jennifer Kaye Whittington

LSU Master's Theses

Pressure-temperature conditions encountered by metamorphic rocks are often used to constrain tectonic environments of formation. Evidence of the prograde path during metamorphism is often obliterated by peak metamorphic conditions. However, pseudomorphs that form during prograde metamorphism may provide insights into heat and mass transport along this portion of the P-T-X-t path. Seventeen sillimanite zone samples, each containing 2-5 muscovite-rich pseudomorphs after staurolite, were investigated from pelitic schists of the Farmington Quadrangle, west-central Maine, USA. Pseudomorphs are easily recognized by an increase in average grain size (~cm) and change to randomly oriented muscovite-rich (~45-75%) modal mineralogy relative to the rock matrix …